Experimental investigation of the hydrodynamic effects upon convecting entropy waves in nozzle flows

The presence of marine growth modifies hydrodynamic effects to subsea structures and could lead to incorrect modelling if not properly accounted for. Widely-used design practice codes do not contain any specific guidelines or recommendations to account for the effects of marine fouling on complex subsea structures and due to the desired longevity of oil and gas constructs, considerable amounts of marine biofouling can accumulate. In the experimental investigation described in the paper, the impacts of different marine growth severities, current velocities and current directions on the hydrodynamic drag were carried out in the Flume Tank at the University of Tasmania. A 1:15 scale mid-water arch (MWA) was employed during this investigation. Several marine biofouling severities were tested as well as the structure without marine growth, representing scenarios based on realistic MWA operating conditions. Physical modelling was validated with numerical simulations using computational fluid dynamics. Experimental results gathered show a rise in drag forces when the artificial marine growth is attached. The highest force magnitudes were observed when the marine growth severity was at its maximum roughness. This has been complemented by numerical results, with input parameters coming from 3D scans of the artificial marine growth.

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Enhancing and suppressing effects of an inner droplet on deformation of a double emulsion droplet under shear

Lab on a Chip ◽

10.1039/c4lc01231c ◽

2015 ◽

Vol 15 (5) ◽

pp. 1255-1261 ◽

Cited By ~ 34

Author(s):

Yongping Chen ◽

Xiangdong Liu ◽

Chengbin Zhang ◽

Yuanjin Zhao

Keyword(s):

Numerical Simulation ◽

Experimental Investigation ◽

Double Emulsion ◽

Emulsion Droplet ◽

Hydrodynamic Effects

We combine experimental investigation with numerical simulation to explore fundamental hydrodynamic effects of an inner droplet on deformation of a double emulsion droplet under shear.

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Numerical and Experimental Investigation Regarding the Landing Manoeuvre of a Catamaran Vessel at an Offshore Wind Turbine in Waves

Volume 7: Ocean Engineering ◽

10.1115/omae2015-42071 ◽

2015 ◽

Cited By ~ 2

Author(s):

Daniel Ferreira González ◽

Matthias Lemmerhirt ◽

Moustafa Abdel-Maksoud ◽

Marcel König ◽

Alexander Düster

Keyword(s):

Experimental Investigation ◽

Time Domain ◽

Offshore Structures ◽

Offshore Wind ◽

Irregular Waves ◽

Offshore Wind Turbine ◽

Reaction Forces ◽

Simulation Results ◽

The Time Domain ◽

Hydrodynamic Effects

In this work, the landing manoeuvre of a catamaran vessel at a monopile foundation is investigated by experiments compared with numerical simulations. Therefore, a method is presented which allows simulating the described landing manoeuvre at offshore structures. The simulation in the time domain is based on potential theory using a boundary element method (BEM) and it computes the motions of the rigid body due to the hydrodynamic loads which consist of the incoming waves and the diffraction caused by the monopile. Further, a fender model is implemented, considering the reaction forces due to the friction and the deformation of the fender. The model is further able to distinguish between slip and non-slip condition of the fender. Apart from this, model tests of the landing manoeuvre were carried out with a catamaran model. During the tests the model pushed its fender against an equally scaled monopile. The motions of the vessel and the forces at the attachment of the fender were measured in regular and irregular waves. The obtained data which leads to a better understanding of the hydrodynamic effects during a landing manoeuvre is compared with the simulation results in order to improve the numerical method. The validation with experimental results shows that the method is applicable to quantify the risk of the fender suddenly slipping.

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